Currently, the direct detection of extrasolar planets (or exoplanets) is extremely difficult. This is primarily because exoplanets appear extremely close to their host stars when observed at astronomical distances. Also, exoplanets are incredibly dim compared to their host stars. Typically, the star will be approximately a billion times brighter than the orbiting planet. This makes it near-impossible to see planets against the star's glare. The difficulty of observing such a dim planet so close to a bright star is the obstacle that has prevented astronomers from directly photographing exoplanets.
It has been proposed to use an occulter to overcome the difficulty of distinguishing a planet in the glare of a bright star. The occulter would block all of the starlight from reaching the observing, while allowing the planet's light to pass undisturbed. This would allow the direct observation of orbiting planets.
The occulter may be a large sheet disc flown thousands of kilometers along the line of sight. The disc would likely be several tens of meters in diameter. One difficulty with this concept is that light incoming from the target star would diffract around the disc and constructively interfere along the central axis. Thus the starlight would still be easily visible, making planet detection impossible. Fortunately this effect can be negated be specifically shaping the occulter. By adding specially shaped petals to the outer edge of the disc, the starlight will disappear, allowing the suppression of the star's light. However, it is a drawback of the prior art that such structures are too large to be launched into space.
Thus, there is a need in the art for an improved structure that may be deployed after it launched into space.